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  • P0088 - Fuel Rail Pressure Too High - Bank 1

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    P0088 - Fuel Rail Pressure Too High - Bank 1

    Theory of Operation

    The Powertrain Control Module (PCM) provides the Fuel Rail Pressure Sensor with a 5-Volt supply and sensor
    ground, and receives a signal voltage back from the Fuel Rail Pressure Sensor. This sensor signal voltage
    changes based on the pressure in the fuel rail. The PCM will light the MIL lamp immediately after the diagnostic
    runs and fails. During this time the customer may experience a power and or speed derate. The PCM will turn
    off the MIL light after the diagnostic runs and passes in four consecutive drive cycles.

    When Monitored and Set Conditions

    When Monitored: This diagnostic runs continuously when the following conditions are met:
    • With the engine running.

     

    Set Conditions:
    • The Powertrain Control Module (PCM) detects that the actual fuel pressure reading is above a calibrated threshold. This DTC will cause active regeneration to be disabled.

     

    Default Actions:
    • The MIL is illuminated.

    Possible Causes

    FUEL CONTROL ACTUATOR
    CHECK VALVE DAMAGED OR BLOCKED
    LOW PRESSURE FUEL SYSTEM SUPPLY
    HIGH PRESSURE FUEL SYSTEM LEAKS
    HIGH INLET RESTRICTION
    FUEL FILTER
    FUEL RAIL PRESSURE SENSOR
    IN TANK LIFT PUMP

    Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTCBased Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    1. OTHER DTCs

    1. With the scan tool, read DTCs. 

    Are any other injector/fuel pressure related DTCs present?

     

    Yes
    • Troubleshoot other injector/fuel pressure related DTCs first.

     

    No
    • Go To 2

     

    2. CHECK THE FUEL DELIVERY SYSTEM

     

    1. Perform the CHECKING THE FUEL DELIVERY SYSTEM procedure. (Refer to 29 - Non-DTC Diagnostics/Drivability - Diesel - Diagnosis and Testing) .
    Did vehicle pass the CHECKING THE FUEL DELIVERY SYSTEM TEST?

     

    Yes
    • Go To 3

     

    No
    • Perform the appropriate repair.
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based
    Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    3. CHECK THE FUEL RETURN LINE

     

    1. Check the Fuel Return line between the Fuel Filter housing and the Fuel Tank for a kink, blockage, or other damage.
    Was there any blockage or other damage found?

     

    Yes
    • Perform the appropriate repair.
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based
    Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    No
    • Go To 4

     

    4. FUEL CONTROL ACTUATOR

     

    1. Check for a mechanically stuck Fuel Control Actuator (FCA). Using the scan tool, actuate the HPCR Duty Cycle Output.
    NOTE: The Fuel Control Actuator will only click when cycled off.
    Do you hear a click from the Fuel Control Actuator when you cycle the actuator off with the scan tool?

     

    Yes
    • Go To 5

     

    No
    • Replace the Fuel Control Actuator in accordance with the Service Information.(Refer to 14 - Fuel System/Fuel Injection, 6.7L Diesel/ACTUATOR, Fuel Control/Removal)
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    5. CHECK VALVE DAMAGED OR BLOCKED


    1. Check the fuel drain line check valve in the rear of the cylinder head for signs of damage, blockage, or debris.
    Is the check valve damaged or blocked?

     

    Yes
    • Repair the cause of the damaged or blocked check valve or replace the valve.
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
     

    No
    • Go To 6

     

    6. FUEL RAIL PRESSURE SENSOR
    1. Using the scan tool, monitor the fuel pressure reading from the Fuel Rail Pressure Sensor at idle and at 2000 RPM.
    Is the fuel rail pressure reading higher at 2000 RPM than at idle?

     

    Yes
    • Repair Complete.

    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

     

    No
    • Replace the Fuel Rail Pressure Sensor in accordance with the Service Information.
    • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


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